EFFECT OF TOPICALLY APPLIED LIPIDS ON SURFACTANT-IRRITATED SKIN

Moisturizers are used daily by many people to alleviate symptoms of dr y skin, All of them contain lipids. It has been suggested that topical ly applied lipids may interfere with the structure and function of the permeability barrier, The influence of a single application of nine d ifferent lipids on normal skin and skin irritated by sodium lauryl sul phate (SLS) was studied in 21 healthy subjects. Parameters assessed we re visible signs of irritation, and objectively measured cutaneous blo od now and transepidermal water loss (TEWL). The substances tested wer e hydrocortisone, petrolatum, fish oil, borage oil, sunflower seed oil , canola oil, shea butter, and fractions of unsaponifiable lipids from canola oil and shea butter. Water was included as a control. On norma l skin, no significant differences in the effects of the test substanc es were found, whereas significant differences were observed when they were applied to SLS-irritated skin. The visible signs of SLS-induced irritation were significantly less pronounced after treatment with the sterol-enriched fraction from canola oil than after treatment with wa ter, This fraction, and hydrocortisone, reduced cutaneous blood now. F urthermore, application of hydrocortisone, canola oil, and its sterol- enriched fraction, resulted in significantly lower TEWL than with wate r, The other lipids had no effect on the degree of irritation. In conc lusion, lipids commonly used in moisturizers may reduce skin reactions to irritants. Previous studies have shown that, in barrier perturbed skin, the synthesis of sterols is increased. The observed effects of c anola oil and its fraction of unsaponifiable lipids on SLS-induced irr itation suggest the possibility that they assisted the skin in supplyi ng the damaged barrier with adequate lipids.